Current electronic systems are typically powered by batteries, continuing energy supplies, or other energy stored devices. This approach is acceptable when it is feasible to replace batteries, when it is connected to the continuous energy supplies, or when it is acceptable to discard the systems when the batteries or stored energy run down. In the cases, if the systems is located in place difficult to get to, or if the system having large number of nodes distributed over large geographic area (e.g. especially communication systems), then that may not possible to replace the stored devices (e.g. batteries) when required. A self sufficient energy generation source (harvesting energy) deriving its power from the environment and thus not requiring any maintenance are desirable in these instances. The energy scavenging device can recharge the batteries. Energy scavenging device helps to run the electronic system for indefinite life time without any maintenance.
Energy can be harvested from several sources to power electronics. (a) Mechanical methods: If motion is available power can be generated from matching the frequency of vibration or discrete impact. Mechanical energy conversion techniques have obtained 250 μw/cm3 at an excitation of 250 mG; (b) RF energy method; If RF signals are present and have sufficient amplitude, energy can be harvested from RF signals; (c) Thermal methods: Thermoelectric devices have successfully been implemented where there are large thermal gradients, usually metal smelters or blast furnaces.
Energy “harvesting” from mechanical, mostly vibration, requires the capture of mechanical energy and conversion into electrical energy. The key requirement for many electrical energy-generating technologies, such as electroactive polymers, is the ability to produce movement against a load (i.e., provide the mechanical work that will be converted to electrical energy). Up to now, attempts to extract such energy have been extremely limited in terms of wattage (i.e., 10-20 microwatts).
More recently, Pelrine et al. suggested in published U.S. Pat. No. 6,768,246 that electroactive polymer devices could be used to generate electrical energy by converting mechanical energy generated by heel strikes during walking into electrical energy. Likewise, energy can be also harvested from RF signal and also from thermal effects. The former requires sufficient RF signal to harvest enough energy to drive the electronic system, and the later requires the thermal differences, which generate the energy on Seebeck effect. However, there are situations where none of these energy sources from where energy can be scavenged, are available. Electronic devices or systems are continually decreasing in energy necessary to operate. Excluding RF, mechanical, and thermal methods of generating energy, there is still energy that can be harvested from the environment to sufficiently power electronic devices.
Energy scavenging based on solar and/or infrared wavelength energy from thermal radiators are developed to efficiently generate power. According to this invention, a novel cost-effective, high efficient environmental scavenger that can scavenge energy at ambient temperature to drive the electronic devices.
In order for energy scavenging to be viable as a future energy source, reliability, and cost of energy scavenging must be comparable with the conventional energy generation sources such as the generators, fuel-cells, or batteries, or their replacement. Currently scavenging energy from environment, sufficient to drive the electronic systems is lagging significantly, in both these areas.
Accordingly, there remains a strong need to develop a device capable of scavenging energy on the order of hundreds of watts, particularly for military applications.
All ambient temperature bodies radiate photons. At environmental temperature, photons have wavelengths between 3 to 14 micrometers, especially in dark situation. In day condition, where appreciable light is present (either sun-light and/or human generated lights) photons have wavelengths from UV (or near UV) to 3.5 micrometers. Significant energy can be harvested 24/7 from these environment-radiation, where photons having wavelengths extending from UV to 14 micrometers, (even over 14 micrometers). Accordingly, there remains a strong need to develop a device capable of generating energy from environment radiation 24/7. The present invention is designed to address these needs in the art.
According to this invention, a device is developed to convert these photons to electrons that could generate enough energy to operate electronic devices. Between 3 and 14 micrometers enough photons are being generated in dark condition, and during day near UV to 3.5 micrometers wavelengths ranges, enough photons are generated which make the device to operate in 24/7. If these photons converted to electrons could harvest significant energy and can power an efficiently designed device. Power that could be generated by efficient conversion is in the tens of milliwatt/cm2 in magnitude.
In this application a design of a device capable to scavenge or harvest the energy from environment radiation is disclosed. Those skilled in the art will appreciate that the principles of the invention disclosed herein, and further defined by the scope of claims to follow, are merely illustrative and are not construed to be limited to specific examples of structure and materials used to explain the principles in this document.